A paper conveying device includes: a registration roller pair provided along a paper conveying path; a pick-up roller, a paper feed roller and a separation roller for feeding sheets of paper to the paper conveying path; and a controller controlling conveyance of sheets of paper such that when a preceding sheet is stopped at the registration roller pair, a following, succeeding sheet is temporarily stopped at a prescribed position G downstream of a conveying roller in the paper conveying direction, and the succeeding sheet is re-conveyed toward the registration roller pair at a prescribed timing. The controller changes the timing to start re-conveyance of the succeeding sheet in accordance with paper length of the conveyed sheet of paper.